Correspondence

Control of Neglected Tropical Diseases

N Engl J Med 2007; 357:2407-2408December 6, 2007

Article

To the Editor:

Hotez et al. (Sept. 6 issue)1 present an excellent review of current global approaches to neglected tropical diseases. However, vigilant ongoing (post-intervention) surveillance to ensure that these diseases do not rebound should not be ignored. The integration of disease-control programs using a “rapid-impact package of drugs” is a feasible and probably cost-effective way to improve the quality of life for billions of people. The authors advocate monitoring and evaluation to judge the success of these programs but do not emphasize ongoing surveillance. Although surveillance may present a resource challenge in many environments, it also poses a statistical challenge as these heterogeneously distributed parasitic diseases become less common. A comprehensive, integrated surveillance plan should be incorporated into the cost estimates for the control or elimination of neglected tropical diseases. New approaches for determining the burden of these diseases as they become less prevalent should include improved diagnostic tools and novel epidemiologic techniques.

Clare Huppatz, B.M., B.S., M.P.H.
National Centre for Epidemiology and Population Health, Canberra 0200, Australia
clare.huppatz@hnehealth.nsw.gov.au

David N. Durrheim, M.B., Ch.B., Dr.P.H.
Hunter Medical Research Institute, Newcastle 2310, Australia

1 References

1. 1

   Hotez PJ, Molyneux DH, Fenwick A, et al. Control of neglected tropical diseases. N Engl J Med 2007;357:1018-1027
   Full Text | Web of Science | Medline

Author/Editor Response

Huppatz and Durrheim comment on the need for surveillance. For the neglected tropical diseases, control and surveillance strategies are determined by the epidemiology and by the precise objectives of the intervention. For example, human African trypanosomiasis was controlled yet resurged during the period from the 1960s to the 1990s in Angola, Democratic Republic of the Congo, and Sudan, because surveillance stopped, health systems collapsed, and the mobile-team approach was abandoned.1 Today, human African trypanosomiasis is again under control, and effective surveillance is crucial in order to avoid a new resurgence. In contrast, soil-transmitted helminthiasis and schistosomiasis require regular preventive mass chemotherapy to reduce severe morbidity, and subsequent monitoring of lot quality assurance sampling is enough.2,3 With lymphatic filariasis, onchocerciasis, and trachoma, surveillance after control must monitor reduction of transmission. The critical tools referred to by Huppatz and Durrheim are being developed or deployed. However, cost and expertise are constraints on routine use, because health systems are overburdened and human resources are scarce where neglected tropical diseases are prevalent. Sadly, introducing routine surveillance of neglected tropical diseases in health management information systems will be challenging, given the diversity of epidemiology and health systems.

David Molyneux, Ph.D., D.Sc.
Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom

Alan Fenwick, Ph.D.
Imperial College London, London W2 1PG, United Kingdom

Lorenzo Savioli, M.D., M.Sc.
World Health Organization, 1211 Geneva, Switzerland

3 References

1. 1

   Human African trypanosomiasis (sleeping sickness): epidemiological update. Wkly Epidemiol Rec 2006;81:71-80
   Medline

2. 2

   Brooker S, Kabatereine NB, Myatt M, Stothard JR, Fenwick A. Rapid assessment of Schistosoma mansoni: the validity, applicability and cost-effectiveness of the Lot Quality Assurance Sampling method in Uganda. Trop Med Int Health 2005;10:647-658
   CrossRef | Web of Science | Medline

3. 3

   Preventive chemotherapy in human helminthiasis — coordinated use of anthelminthic drugs in control interventions: a manual for health professionals and programme managers. Geneva: World Health Organization, 2006.